A Framework for Conferencing with the Session Initiation Protocol (SIP)
RFC 4353
Document | Type | RFC - Informational (February 2006; No errata) | |
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Author | Jonathan Rosenberg | ||
Last updated | 2015-10-14 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4353 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Allison Mankin | ||
Send notices to | rohan@ekabal.com, dean.willis@softarmor.com |
Network Working Group J. Rosenberg Request for Comments: 4353 Cisco Systems Category: Informational February 2006 A Framework for Conferencing with the Session Initiation Protocol (SIP) Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The Session Initiation Protocol (SIP) supports the initiation, modification, and termination of media sessions between user agents. These sessions are managed by SIP dialogs, which represent a SIP relationship between a pair of user agents. Because dialogs are between pairs of user agents, SIP's usage for two-party communications (such as a phone call), is obvious. Communications sessions with multiple participants, generally known as conferencing, are more complicated. This document defines a framework for how such conferencing can occur. This framework describes the overall architecture, terminology, and protocol components needed for multi- party conferencing. Table of Contents 1. Introduction ....................................................2 2. Terminology .....................................................3 3. Overview of Conferencing Architecture ...........................6 3.1. Usage of URIs ..............................................9 4. Functions of the Elements ......................................10 4.1. Focus .....................................................10 4.2. Conference Policy Server ..................................11 4.3. Mixers ....................................................11 4.4. Conference Notification Service ...........................12 4.5. Participants ..............................................13 4.6. Conference Policy .........................................13 5. Common Operations ..............................................13 5.1. Creating Conferences ......................................13 5.2. Adding Participants .......................................14 Rosenberg Informational [Page 1] RFC 4353 Conferencing Framework with SIP February 2006 5.3. Removing Participants .....................................15 5.4. Destroying Conferences ....................................15 5.5. Obtaining Membership Information ..........................16 5.6. Adding and Removing Media .................................16 5.7. Conference Announcements and Recordings ...................16 6. Physical Realization ...........................................18 6.1. Centralized Server ........................................18 6.2. Endpoint Server ...........................................19 6.3. Media Server Component ....................................21 6.4. Distributed Mixing ........................................22 6.5. Cascaded Mixers ...........................................24 7. Security Considerations ........................................26 8. Contributors ...................................................26 9. Acknowledgements ...............................................26 10. Informative References ........................................27 1. Introduction The Session Initiation Protocol (SIP) [1] supports the initiation, modification, and termination of media sessions between user agents. These sessions are managed by SIP dialogs, which represent a SIP relationship between a pair of user agents. Because dialogs are between pairs of user agents, SIP's usage for two-party communications (such as a phone call), is obvious. Communications sessions with multiple participants, however, are more complicated. SIP can support many models of multi-party communications. One, referred to as loosely coupled conferences, makes use of multicast media groups. In the loosely coupled model, there is no signaling relationship between participants in the conference. There is no central point of control or conference server. Participation is gradually learned through control information that is passed as part of the conference (using the Real Time Control Protocol (RTCP) [2], for example). Loosely coupled conferences are easily supported in SIP by using multicast addresses within its session descriptions. In another model, referred to as fully distributed multiparty conferencing, each participant maintains a signaling relationship with the other participants, using SIP. There is no central point of control; it is completely distributed amongst the participants. ThisShow full document text